Water heaters normally include a steel tank to contain water to be heated, and to prevent corrosion of the steel tank, a corrosion resistant coating, such as glass or porcelain enamel, is applied to the inner surfaces of the tank which are exposed to the water. As intensified corrosion can occur through defects in the glass coating or in areas of the steel tank that may be inadequately coated, it is common practice to suspend an anode rod of a metal electronegative to steel, such as magnesium, aluminum or zinc, in the tank. The anode, being electronegative to steel, will corrode preferentially to prevent corrosion of any areas of the steel tank exposed through the corrosion resistant coating.
To mount the anode rod in the tank, it is common practice to weld an annular, internally threaded spud to the outer surface of the tank head bordering an opening in the tank head. The anode rod, which is carried by a steel cap, is inserted through the opening in the tank head and the cap is threaded within the spud to mount the anode in the tank.
The conventional anode rod has a steel core wire and the upper end of the core wire projects beyond the corresponding end of the anode rod and is connected electrically to the cap either by welding or upsetting. With this construction, the anode rod will be suspended within the tank and will be electrically connected through the cap and spud to the tank wall.
The conventional anode cap, having a central axial opening to receive the anode rod, an enlarged head with wrench flats, and external threads, is manufactured from solid bar stock by machining operations which is a slow and costly procedure.